30, 2. Analysis: Yide A 1A2 is the root 2 of 10, and the northwest of angle A 120 degrees is 60, so A 1A2 is the root 2 of 10. The angle B 1A 1A2 is 105 degrees, and the angle B2A 1A2 is 60 degrees, so the angle B2A 1B 1 is 45 degrees. It is known that A 1B 1 length 20. According to the cosine theorem (I don't know how to search on Baidu Encyclopedia), we can know the length of B 1B2 10. After another 20 minutes, which is one third of 1 hour, speed = distance ÷ time, so the answer is 30 radicals 2.